Telephone party-line system.



J. ERICKSON. TELEPHONE PARTY UNE SYSTEM. APPLICATION map SEPT. 15. 1906.

1 1mm Patented Apr. 25,1916.

l; I E Q a i I e I E W Q mm mwuw L w a a. A f V 0; an 1 5;.

rans a l.

JOHN ERICKSON; OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FIRST TRUST AND SAVINGS BANK, TRUSTEE, OF CHICAGO, ILLINOIS.

TELEPHONE PARTY-LINE SYSTEM.

Ll.8ll,ll93.

Specification of Letters latent.

Patented Apr. 25, 11916.

Application filed September 15, 1906. SeriaI No. 334,768:

To all whom it may concern Be it known that 1, JOHN Enronson, a

citizen of the United States of America, and

resident of Chicago, (ook county, Illinois, have invented a certain new and useful Imr prmemcnt in lelephonc .u y-nne ys My invention relates to automatic telephone exchange systems of that particular type in whiclrthe subscribers use ground connections at the substations for transmltting electrical impulses over the telephone lines to operate the selectors and connectors and for thus preventing the calling subscribers lock-out relay from becoming energized by the sudden connection of all the substation condensers in multiple with the grounded pole of the battery; for in cases where several. substations are located on a line, necessitating the use of a corresponding number of cgmdcnscrs bridged in parallel across the line, I find that the total capacity is so great that a static charging is liableto occur, sullicient to energize the look-out relay of the calling subscriber, even though the telcphone'linc is freeand in normal condition; and it is for this reason that the principal object of my invention is, as I say, to provide means fo'rcnablmg the subscriber on a party line, when the latter is not in use, to take down his receiver without causing such a static charging of the condensers on the line as will be liable to energize his lock-out relay, as will hereinaftermore fully appear.

- It is also an object, of course, to provide certain details and featuresof improvement and combinations which may be found usepems, of which the following is a specificalion.

ful in various connections and for various purposes in telephone systems in general.

To the foregoing and other useful ends, my invention consists in matters hereinafter set forth and claimed.

In the accompanying drawings, Figure 1 is a diagram of a section of a telephone systern embodying the principles of invention. In'said figure a number of party line telephones" A, B, C and D are indicated across the line that'terminates in a step-by step automatic switch E at the central oilice. Fig. 2 is also a diagram showing more in detailthc application of my invention to an automatic party line telephone system, only two substations A and B being shown.

The telephones A and 13 shown in Fig. 2 may be of any suitable or approved type; The automatic switch E may also 'be of any suitable type, such as the selector described in United States Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson and Erickson. In the said patent the sub scribefisvertical and rotary line conductors 2 and 3 terminate directly in therespectivc vertical and rotary line relays 4: and 5. As herein shown, the connections are modified to the extent that the rotary line conductor 3 terminates in a switch shaft spring 6 controlled by the switch shaft 7, which spring, when the switch shaft is raised, engages the spring 8, at which time the rotary line conductor 3 is extended to the rotary line relay 5, as usual; but when the switch shaft is in normal position the said spring 6 is maintained in engagement with the spring 9 and, therefore, with the higlrresistance coil 10 which is grounded at G. v

The substation is provided with the usual receiver 11, transmitter 12 and switch-hook 13, and. also with the ringer l-l that is normally bridged across the line conductors 2 and 3 through the-condenser 15. When the switch-hook 13 rises, however, the ringer circuit that passes through the ringer springs 16 and 17 is broken, since the said springs are adapted to separate when the 10 weight of the switch-hook is removed from the spring 16. The telephone is provided with a dial (which is not shown) providedf with numbers on its circumference, and witli suitable finger-holes for ji guiding the subscriber in sending electr c impulses for 0pcrating. the switches at the central ofiice. To accomplish this the dial must be rotated first clockwise and then allowed to return to normal position by a counter-clockwise rotation. The dial is fastened onto the shaft 18 to which there is also attached a dog 19. The substation is provided with a lock-out relay 20 that is constructed with an elongated-armature 21. This armature is provided with a hooked terminal that'is adapted to engage an eye in the dog 19, and the arrangement is'such that when the relay 20 energizes the armature 21 is attra'ced and the dog 19 is locked by said armatureso that the subscriber is unable to turn his dial. It is intended that this locking operation shall only occur after the first subscriber that seizes the line operates the selector switch. E so as to close the normally open circuit between the switch shaft springs 6 and 8.. Since the energizing circuit for the relay 20 comprises the said springs 6 and 8 it will be evident that said relay should not energize until the said springs are in contact. It happens, when there are a great number of substations bridged across the line, as indicated in Fig. 1, that the condensers 15 (which are connected inmultiple) aggregate a capacity which permits a current flow from the substation ground G at substation A through the coil 20, springs 22 and 23 to the rotary line conductor 3, thence to the conductor 24 at substation B, through the ringer springs 25 and'26, through the ringer 27 condenser 15 to the vertical line conductor 2, thence through the vertical line relay & at the switch E to the battery B and to the ground. A similar discharge would occur through the station 0, station D, and

so on. When there are only a couple of substations across the line this trouble from a discharge may not become apparent, but as the number of substations increases it becomes more and more apparent: It is found connecting the substation relay 20 with the rotary lineconductor 3, when the springs 22 and 23 close in contact, does not operate the relay 20. It will thus be very evident that my invention thus considered is applicable to any kind of a line Where a relay maybe energized by the discharge through ia condenser, or condensers in multiple, or

otherwise. This, as stated, the condensers on the artyjline are normally charged, and. the su den closure of connection between ground and a substation on the line does not, therefore, tend to ene' gize the lock-out relay of the calling subscrioerthati is to say, in cases where the line is cleaf or in normal condition, and the calling subscriber entitled to the use of .-.Furbherm "itswill be seen that I provide a telephone charged from the positive pole of the battery, and the adding of another ground atthe calling substation, when the subscriber removes his receiver, does not produce a current flow through the condensers.

While my invention, as previously stated, relates more particularly to automatic party line telephone systems, it will be understood, of course, that I do not limit myself to systems of this particular character,

as my invention is also applicable toother systems, either automatic or otherwise, such, for example, as ordinary manual systems in which provision is made for locking the calling subscriber out when the line is already in use, or in which electro-ma gnets for some suitable purpose are employed at the substations. I

What I claim as my invention is 1. In a telephone exchange system, the combination of atelephone line, a plurality of substation condensers bridged in parallel across said line, a normally open substation ground associated with each condenser, an' electro-magnet associated with each condenser, means for closing circuit fromground through the coil of the electromagnet'to the condensers in parallel when the calling subscriber takes down the receiver associated with such magnet, acontralized source of current having one pole grounded, and a normally' closed ground connection for one side of the telephone line, said line being normally disconnected at one side .from the non-grounded pole of the source of current, and normally connected with the non-grounded pole of said source of currei'it at the other side thereof.

2. In a telephone exchange system, the combination of a telephone line, calling mechanism therefor, a common battery having one pole grounded and the other pole normally connected with the line, a noniii 1,181,093 :llslt battery having one pole grounded and the other pole normally connected with the line, an automatic trunk-selecting switch having a normally,closed connection between one side of the line and the grounded pole of the battery at the central station, a resistance in said connection, and means for disconnecting said resistance during talking.

a. In a telephone exchange system, the combination of a telephone line, a plurality of substations on said line, a'condenser at each substation, said condensers being in multiple, a battery at the central station, an automatic selecting switch for extending a connection from said line, and means for keeping said condensers charged with battery current while the line is in normal condition, each condenser normally connected with and between both poles of the battery, and said battery normally bridged across the subscribens telephone line, for the purpose set forth.

In a telephone exchange system, the combination of a telephone line, a plurality of substations on said line, a condenser at each substation, an electro-magnet at each suliistation. a central source of current, a hook-switch for each substation, means for closing circuit through all the condensers in parallel, and through one magnet, when a subscriber takes down his receiver, and means for preventing energizing of the one magnetby current flow through the condensers in parallel.

6. In a telephone system, a battery, a

line having its two sides normally connected with opposite sides oi? said battery, a plurality of condensers normally bridged across the said line. an impulsetransmitter, and meansby which acalling subscriber, by the first" rn'ipulse transmitted, disconnects one side of the line from one pole to the battery and connects the same with the other pole thereof.

7. In a telephone system, a telephone line. a plurality of condensers normally bridged across the HHHI'. a battery having one pole grounded and the other pole connected with one side of the line, the other side of the line being grounded, an impulse transmitter. and means by which a calling subscril'lcr. by the first impulse transmitted, cuts oil the ground from the line and connects that side of the line with the. non-giournled pole of the battery.

f a teiephone system. a battery, a plu rality of condensers connected in parallel in a normally clo .(l line circuit containing said battery, an imp transmitter, and means at the central station by which a calling subscriber at any condenser disconnects one pole of the l til'tcl'j. and connects the disconnected side of the circuit with the otherpolc thereof on. the first impulse transmitted.

J. In a telephone exchange system, the

combination of a telephone line, a plurality of substation condensers bridged in parallel across said line, a normally open substation ground associated with each condenser, an electromagnet associated with each condenser, means for closing circuit from ground through the coil. of the electromagnet tothe condensers inparallel when the calling subscriber takes down the receiver associated with such magnet, a centralized source of current having one pole grounded,

a normally closed ground connection for'onc side of the telephone line, and means having one motion to select groups and another motion to connect with a line in any se- 8o lected group, responsive to grounding of the line at any calling substation.

10. In a telephone exchange system, the combination of a telephone line, a common battery having one pole grounded and the other pole normally connected with one side of said telephone line, relay windings included in the connection between the line and the non-grounded pole of the battery,

a normally closed connection between one side of the line and the groundedpole of the battery, the line being normally open between the said ground connection and the battery connection, subscriber-controlled means for opening said ground connection, and means having one motion to select groups and another motion to connect with a line in any selected group, responsive to grounding of the line at any calling substation.

11. In a telephone exchange system, the combination of a telephone line, a plurality of substations on said line, an electromagnet at each substation, a condenser at each substation, a battery at the central station, means for keeping said condensers charged with battery current while the line is in normal condition, there being a circuit from each magnet through the condenser-sin multiple and to the battery, and means having one motion to select groups and another motion to connect with a line in any selected group, responsive to groimding of the saidv telephone, line.

12. In a telephone exchange system, the combination of a telqahoiie line, a plurality of condensers and substations allotted. thereto, means for locking-out a calling substation it the line is in use, and means whereby any calling substation is not locked out. when the line. is idle; the first said means con'iprising a battery, a subscribers line, a substation magnet, and a normally open circuit for energizing said magnet, including the said battery and sul'iscril'iers line; the 126 second said means comprising a battery, the subscribers line, condensers connected with one terminal of said battery, and a resistance-coil allotted to the line and connected to the other terminal of the battery, the said 1M battery adapted to charge the said condens- V having one motion to select ers over a circuit including the s.ubscribers line and the said resistance-coil; and means groups and another motion to connect with a line in any selected group, responsive to grounding of the line at any calling substation.

13. In a telephone exchange system, the combination of a telephone line, a plurality of substations on said line, a condenser at each substation, an electromagnet at each substation, a central source of current, a hook-switch for each substation, means for closing circuit through all the condensers in parallel, and through one magnet, When with a line in any selected group, responsive to grounding ofthe line at any calling substation.

Signed by me at Chicago, Cook county, Illinois, this-12th day of September, 1906.

JOHN ERICKSON.

Witnesses:

EDWARD D. FALES, BERNARD D. VVILLIs. 

